import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';

import '../components/CategoryTitle.dart';
import '../components/PageWrap.dart';

class WrapAndFlowLn extends StatefulWidget {
  const WrapAndFlowLn({super.key});

  @override
  State<WrapAndFlowLn> createState() => _WrapAndFlowLnState();
}

class _WrapAndFlowLnState extends State<WrapAndFlowLn> {
  @override
  Widget build(BuildContext context) {
    return PageWrap(
      title: "流式布局（Wrap、Flow）",
      children: <Widget>[
        CategoryTitle(text: "Wrap"),
        Wrap(
          spacing: 8.0, // 主轴(水平)方向间距
          runSpacing: 4.0, // 纵轴（垂直）方向间距
          alignment: WrapAlignment.center, //沿主轴方向居中
          children: <Widget>[
            Chip(
              avatar:
                  CircleAvatar(backgroundColor: Colors.blue, child: Text('A')),
              label: Text('Hamilton'),
            ),
            Chip(
              avatar:
                  CircleAvatar(backgroundColor: Colors.blue, child: Text('M')),
              label: Text('Lafayette'),
            ),
            Chip(
              avatar:
                  CircleAvatar(backgroundColor: Colors.blue, child: Text('H')),
              label: Text('Mulligan'),
            ),
            Chip(
              avatar:
                  CircleAvatar(backgroundColor: Colors.blue, child: Text('J')),
              label: Text('Laurens'),
            ),
          ],
        ),
        CategoryTitle(text: "Flow"),
        ConstrainedBox(
          constraints: BoxConstraints(maxWidth: MediaQuery.of(context).size.width),
          child:  Flow(
            delegate: TestFlowDelegate(margin: EdgeInsets.all(10.0)),
            children: <Widget>[
              Container(width: 80.0, height:80.0, color: Colors.red,),
              Container(width: 80.0, height:80.0, color: Colors.green,),
              Container(width: 80.0, height:80.0, color: Colors.blue,),
              Container(width: 80.0, height:80.0,  color: Colors.yellow,),
              Container(width: 80.0, height:80.0, color: Colors.brown,),
              Container(width: 80.0, height:80.0,  color: Colors.purple,),
            ],
          ),
        )

      ],
    );
  }
}



class TestFlowDelegate extends FlowDelegate {
  EdgeInsets margin;

  TestFlowDelegate({this.margin = EdgeInsets.zero});

  double width = 0;
  double height = 0;

  @override
  void paintChildren(FlowPaintingContext context) {
    var x = margin.left;
    var y = margin.top;
    //计算每一个子widget的位置
    for (int i = 0; i < context.childCount; i++) {
      var w = context.getChildSize(i)!.width + x + margin.right;
      if (w < context.size.width) {
        context.paintChild(i, transform: Matrix4.translationValues(x, y, 0.0));
        x = w + margin.left;
      } else {
        x = margin.left;
        y += context.getChildSize(i)!.height + margin.top + margin.bottom;
        //绘制子widget(有优化)
        context.paintChild(i, transform: Matrix4.translationValues(x, y, 0.0));
        x += context.getChildSize(i)!.width + margin.left + margin.right;
      }
    }
  }



  @override
  Size getSize(BoxConstraints constraints) {
    // 指定Flow的大小，简单起见我们让宽度尽可能大，但高度指定为200，
    // 实际开发中我们需要根据子元素所占用的具体宽高来设置Flow大小
    return Size(double.infinity, 200.0);
  }

  @override
  bool shouldRepaint(FlowDelegate oldDelegate) {
    return oldDelegate != this;
  }

}
